Red John is definitely Thomas McAllister. Now I will explain why.

1 - The actor who plays TM, Xander Berkeley (http://www.imdb.com/name/nm0075359/) has done voice work in his career, this means that he will be able to perform the weird Red John voice we have heard throughout.
2 - He is scared of pigeons/birds, this is why he had to leave Lisbon, the pigeons were scaring him, this is the fear the he was hiding from the psychologist (he claimed to be afraid of heights due to it being way more generic, so less identifiable). Pigeons have been hinted at all the way through the season in the promo for the next episode there is a pigeon sitting in the hand of a statue in the church.
3 - He is easily old enough to be at the barn and be RJ.
4 - Download the 'Red John - S06E08' trailer and play it frame by frame, look at when RJ crashes through the window. This is McAllister, there is no doubt about it. The hairline is exactly the same.
5 - Also I have rewatched some of the RJ episodes and paying loads of attention and if you look when RJ saves Jane (S02E23), he is wearing heeled boots. Who else wears heeled boots but sheriffs? Although this may be insignificant as I doubt it was thought about that much.
6 - Faking a death in an explosion is easy as pie. McAllister is pretty old so has probably got fake teeth so the one identifier on charred bodies is not working (ok, this is a bit of a stretch). We were given no real confirmation they were really dead, we saw one foot that's it.

I must also say why I don't believe it was others.

Bertram - Too obvious, next episode was always going to be the big reveal, Jane only released his name so he could take attention off of him to work alone. Why would he give up his vengeance so some randomer can kill/capture RJ?

Reede Smith - If this needs to be explained to you, how about you go and actually watch the show.

Brett Partridge - Dead. Tattoo cut off for security reasons. Guy was an absolute weirdo so got in TygerX2 because he needed someone to cover up for him doing some WEIRD stuff.

Kirkland - Really dead. Don't think it's him. Twin must have some significance? Or just something to put us off.

Bret Stiles - Too old, British accent is identifying although could be hidden. Not much against him but I've not got much the other way either, so he stays a second option.

Ray Haffner - He just doesn't fit. Seems as though he was brought in to fill up the list really. My main point against him is that he holds little power, the rest, bar Smith, do.

I probably left out loads of things I should have written, but anyway, now you know who RJ is. Thank me later.

Did anyone else notice the teacup?  In a season finale a couple years ago, when a redjohn accomplice had Jane in the basement of a house, Lisbon rescued him before Jane was ready.  They showed the upstairs where there was a half used teacup sitting on the kitchen table and the patio door closing.  I think it was the same teacup that Jane was drining out of last night that the FBI guy knocked it out of his hands.  Jane said "hey, that's my favorite teacup."

My thinking is that Jane knows from the teacup who RJ is.  He now has DNA for the 5 "dead" people to run the DNA from the teacup against.

At this point, there are very few things I'm very positive about.  1 is that Reede Smith is NOT RJ.  Jane interviewed him and dismissed him and as Bruno Heller put it, if Jane says it's true, you can take it for face value.  2 RJ is the leader of Tiger, Tiger.  It's his organization to cover his tracks using dirty cops who are afraid of being discovered.  3.  The FBI was sent in to close down the CBI as a Tiger, Tiger order. 4.  There's more to Partridge's tattoo being cut off than his tattoo being cut off.  There was too much emphasis on it, and Jane deflected Lisbon's question, which tells me to pause there.  5.  Jane taking the gun from his house hasn't played yet.  6.  Jane knows who RJ is at this point and is going to the church to let things play themselves out. 

Beyond that McCallister is a guess.  There are at least 3 plot twists coming in the next episode and the first reveal is DEFINETLY NOT going to be RJ unless there is an end-story followed by back story.

Yeah, so it's pretty clear now, isn't it? After watching the extended promo, I think this is how it's gonna be in 6x08:

1. McCallister joins Patrick in church, they have a nice talk, one of those "mentalist" conversations. (I wonder when did Patrick realize that McCallister survived the esplosion, because I'm sure he knew that Sheriff is Red John by the time he decided to go to church) ;)

2. Patrick shoots McCallister, but for some reason doesn't kill him. If I didn't see the promo, I would think that Patrick would spare him for some reason, or just let him live for some time, or maybe decided to give him to the police, but now I'm pretty sure that McCallister just manages to escape somehow..

3. The final man hunt begins. At one point, McCallister "visits" some house, enters it by breaking through glass door, as we see in promo. He bleeds, because of the events in church. 

4. a) Later, both Patrick and McCallister are on the graveyard, McCallister is running from Jane. The question is: what were they doing on the graveyard? How did they get there?

b) Jane's team and the FBI are also on the scene somehow, not sure what role they play yet.

5. As we know, in the end Patrick strangles Red John. We didn't know how would he manage to do it, since pretty much every suspect was stronger than Jane. Now we know  - McCallister is wounded very seriously and Patrick can probably overpower him easly.  

And I guess that's how it goes I guess. Except... maybe McCallister is not Red John? I mean... Well, we all agree, that Bertram is not Red John, because it's too obvious. So because we are all here so very super smart, we found out, that McCallister must be Red John. Don't get me wrong, I'm almost sure, that the mysterious guy in the promo is McCallister... but maybe it's not Red John? Maybe that's just the final, ultimate red herring? The final trick? That would be something right?  :) I would very much like that... Or maybe after 6 1/2 seasons I getting a little paranoid? ;) Well, we'll see.

Ok, so, firstly, for all of those people that think Red John is Bertram:

- it  would make sense, but it is definitely too obvious for it to be him because the mentalist is known for it's plot twists.

- and if it was Bertram, then at the end of season 3 (Strawberries & cream) then the assassin sent to kill hightower would have gone to the room that they told bertram she was staying to find the CBI Red John accomplice that burnt Todd Johnson alive (granted, she did go to that room but it was only so she could climb to the other room with the rope). as Bertram is part of the Blake association, then the assasin could've been ordered to check both rooms for Hightower, this one was just a mixed up thought that i haven't described well haha.

but i think bertram is more than just a tool for red john, he is closer to him.

so, i think that if red john is anyone on the list, then sheriff mcallister is red john because:

Firstly, He is alive, and one of the bodies found after the explosion wasn't him. Say he is red john, then he wouldn't bring a bomb into Jane's house without a backup plan. He is cleverer than that. So he makes the world think that he is dead in order to draw away the suspicion that he is red john. Also, an interview i read somewhere, went something like this:

Interveiwer: so are we sure that those three died in the fire? and it wasn't a trick/plot twist?

Writer: well, yes, is was real bodies in that house, but there are some surprising turns coming up regarding the explosion.

notice how he dodged the question and gave it away a bit?

-in last nights episode (The Great Red  Dragon) Bertram went to a vault storage room thingy by the name of Thomas (which i think is Sheriff Thomas Mcallister) and my theory was confirmed when there was wine bottles in there, because Napa is the wine country!

So you may be thinking 'say that is McAllisters Storage room, that doesn't mean he's Red John' 

well, there are several reasons why this could mean that he is Red John. Firstly, he could've contacted Bertram and asked for a favour (which he had to do as part of the blake association) to go into his storage and get passport, money etc. and plant the fake lighter USB stick with a code message, knowing that jane would solve it (i suspect it told him to meet him in the church because jane doesn't believe in God so why would he go to a church, and he wouldnt just let go of the RJ investigation like that after 10 years of devoting his life to it, so just told Lisbon he was giving up for the same reason he left her by the sunset and drove off in 'Fire and Brimestone')

And also, if you look really closely, after Bertram opens the box in the storage room, when he lifts out the straw-like packaging first, i think you can see that buried in the straw packaging, there is RJ's signature knife (the weird shaped one RJ is seen holding in many scenes).

so yeah I guess thats why I think it's Thomas McAllister

Also, does anyone have a theory for why there are pigeons emphasised in loads of scenes (the scene in the house where partridge was found dead, in the promo for 6x08 on the angel made of stone in the church and various other scenes)

This is probably all wrong but thank you for reading and feel free to comment! :)

Well I was 100% partridge for a looooooong time.

Until someone posted this on imdb. Way more convincing than the "busting through the glass" picture.

If this doesn't convince you it's Mccallister.....nothing will

http://s21.postimg.org/q708c39yv/image.jpg

Game set match.

Ok, so, firstly, for all of those people that think Red John is Bertram:

- it  would make sense, but it is definitely too obvious for it to be him because the mentalist is known for it's plot twists.

- and if it was Bertram, then at the end of season 3 (Strawberries & cream) then the assassin sent to kill hightower would have gone to the room that they told bertram she was staying to find the CBI Red John accomplice that burnt Todd Johnson alive (granted, she did go to that room but it was only so she could climb to the other room with the rope). as Bertram is part of the Blake association, then the assasin could've been ordered to check both rooms for Hightower, this one was just a mixed up thought that i haven't described well haha.

but i think bertram is more than just a tool for red john, he is closer to him.

so, i think that if red john is anyone on the list, then sheriff mcallister is red john because:

Firstly, He is alive, and one of the bodies found after the explosion wasn't him. Say he is red john, then he wouldn't bring a bomb into Jane's house without a backup plan. He is cleverer than that. So he makes the world think that he is dead in order to draw away the suspicion that he is red john. Also, an interview i read somewhere, went something like this:

Interveiwer: so are we sure that those three died in the fire? and it wasn't a trick/plot twist?

Writer: well, yes, is was real bodies in that house, but there are some surprising turns coming up regarding the explosion.

notice how he dodged the question and gave it away a bit?

-in last nights episode (The Great Red  Dragon) Bertram went to a vault storage room thingy by the name of Thomas (which i think is Sheriff Thomas Mcallister) and my theory was confirmed when there was wine bottles in there, because Napa is the wine country!

So you may be thinking 'say that is McAllisters Storage room, that doesn't mean he's Red John' 

well, there are several reasons why this could mean that he is Red John. Firstly, he could've contacted Bertram and asked for a favour (which he had to do as part of the blake association) to go into his storage and get passport, money etc. and plant the fake lighter USB stick with a code message, knowing that jane would solve it (i suspect it told him to meet him in the church because jane doesn't believe in God so why would he go to a church, and he wouldnt just let go of the RJ investigation like that after 10 years of devoting his life to it, so just told Lisbon he was giving up for the same reason he left her by the sunset and drove off in 'Fire and Brimestone')

And also, if you look really closely, after Bertram opens the box in the storage room, when he lifts out the straw-like packaging first, i think you can see that buried in the straw packaging, there is RJ's signature knife (the weird shaped one RJ is seen holding in many scenes).

so yeah I guess thats why I think it's Thomas McAllister

Also, does anyone have a theory for why there are pigeons emphasised in loads of scenes (the scene in the house where partridge was found dead, in the promo for 6x08 on the angel made of stone in the church and various other scenes)

This is probably all wrong but thank you for reading and feel free to comment! :)

1) For the Partridge friends -- It can't be him because he's wrapped in plastic.  I think Cho would have noticed if it wasn't Partridge.

2) Bertram is a bad man, but I don't think he's RJ although he is my obvious #2 suspect.

3) The shots we see of RJ in this episode look more like McAlister.

4) As I've said for a few weeks, McAllister is the only character with a listed age for his character that doesn't just assume the age of the actor playing him.

5) He's been there from the start.

Arguments for Bertram -- he was there in the mall with Jane (we were told we would see RJ), but we were also told we would catch a glimpse of RJ and that seemed like more than a glimpse.

6) Bertram doesn't seem crafty enough to be RJ where as the Sheriff does seem crafty enough.